This project will study occupational fertility differentials and their determinants in an historical and comparative context. Countries to be studied include the United States, England and Wales, Belgium, and Germany. Emphasis will be on one high fertility occupational group, coal miners, but comparisons will be made with other socio-economic and occupational groups. Studies underway or proposed include areal analyses of small geographic units with high concentrations of coal mining (for England and Wales in 1851, 1861, and 1871; for Belgium for census dates between 1846 and 1910; and for Germany in 1882, 1895, and 1907). Further, micro-level analyses will be conducted with the U.S. censuses in Pennsylvania; with the 1865 census of New York State for seven counties; with an 1889/90 survey of workers in coal mining and five other industries in the U.S. and Europe by the U.S. Bureau of Labor; and with the population registers of one mining commune in mid-nineteenth century Belgium. Hopefully, the study will contribute to greater understanding of the role of various socio-economic and demographic factors in household fertility decision and to an improved picture of the fertility decline in several presently developed nations.